Could photovoltaics hit 50% efficiency? Spectrolab in Sylmar, CA is
gunning for it with a record high 40.7% conversion rate from their
latest solar cell. Spectrolab’s solar panels are similar to those from Soliant Energy, concentrating light onto solar cells using mirrors and lenses. However, Spectrolab goes beyond the typical
silicon based solar cell: theirs have three layers of semiconductors, each
capturing different parts of the electromagnetic spectrum.

Though
this idea is not completely new – layered solar cells are used in space
already – in the past these layers could only be made using a limited
number of semiconductor materials. Now, Spectrolab has developed the
use of "metamorphic" materials, allowing them to explore new structural
possibilities and ramp up the efficiency of their cells.

…device designers have until recently employed only a limited repertoire of semiconductors, such as germanium and gallium arsenide, which form similar crystal structures. Metamorphic materials provide flexibility by throwing off this structural constraint, employing a wide range of materials, including those with mismatched structures. "The parameter space you can explore using mismatch opens up a whole world of possibilities," says NREL principal scientist Sarah Kurtz.

Since
the use of metamorphic materials is new, there still is a lot of
potential left. Let’s hope we see those results soon, so that we can
all enjoy more energy and smaller solar panels.